davis



4 Sheets-Sheet 1.

(No Model.) C. H. DAVIS.

RAILWAY SIGNALING SYSTEM.

No. 606,450. Patented June28,1898.

INVENTOR (No Model.) 4 Sheets-Sheet 2.

C. H. DAVIS. RAILWAY SIGNALING SYSTEM.

No. 606,450. Patented June '28, 1 898.

WITNESSES: INVENTOR w: cams PiFEI'IS cu. wamuruo WASHINGTON, s, c

' (No Model.) 4 sheets- -sheet 3. 1 0,11. DAVIS. RAILWAY SIGNALING SYSTEM.

No. 606,450. Patented June 28,1898. 594

WITNESSES: A INVENTQR K ATTIORNEY Ens co Pumouma, wASNmoTON n c (No Model.) I 4 sheets sheet 4.

O. H. DAVIS. RAILWAY SIGNALING SYSTEM.

PatentedJune 28, 1898.

I WITNESSES: mvamon e q%? BY w A TORNEY ATENT CHARLES H. DAVIS, OF NEW YORK, N. Y.

:RAILWAY SIGNALING SYSTEM.

SPECIFICATION forming part of Letters Patent N .606,450, and June as, 1898. v a lication fil d December 29, 1897. Serial No. 664,195. (No model.)

To all whom it may concern:

Be it known that LOHARLEs H. DAVIS, of

the city, county, and State of New York, have invented a new and" useful Improvement in Railway Signaling Systems, of which the fol-' lowing is a specification. My invention is a signaling system designed to meet the conditions of high-speed trains on railways and in such a way as to permit of the maximum number of trains consistent with safety to occupy the line.

The invention is especially applicable to railways whereon the trains are driven by electricity and at velocities which may reach or even exceed one hundred and seventy miles per hour.

The invention consists, broadly, in the combination, in a railway signal system, of a rail way-line, a series of signaling devices in proximity thereto, each device being constructed to exhibit a danger-signal and a safety-signal,

and interlocking mechanism connecting each device with two or more immediately-succeeding signal devices, the said signaling devices being constructed and arranged so that a given device cannot be set to exhibit a safety-signal until it shall have exhibited a danger-signal as manytimes as there are succeeding devices interlocked with it and unless said succeeding devices shall previously have been set to exhibit danger.

This-invention I may embody in various forms of apparatus. The signaling devices may be of any kind capable of conveying the necessary information for the purposes set forth. The interlocking mechanism may be either mechanical'or electrical, or both. The apparatus may be actuated manually or by any other means adapted to the purpose.

In my present application I illustrate one operative and practical means and the best I now know for carrying my invention into effect; but it is to be distinctly understood that I- do not limit myself (save in the claims where such limitation is expressly made) to the specific apparatus herein set forth. In said specific apparatus I exhibit visual signaling devices, each consisting of a fourarmed cross pivoted at its center and provided with any suitable means for rotating it, so as to bring each arm of the cross successively into signaling position-as, for examfour-armed signaling cross and post.

ple, horizontally above and near the track.

Three ofthe arms are suitably colored to indicate danger when exposed. The other isalso suitably colored to indicate safety.

On the shaft of each cross is a barrel-commutator arranged to close certain circuits when the cross is'in each of its four positions and also an electromagnetic lockingdevice which is included in certain electric circuits with other crosses. Suitable circuit connections are provided between the severalsignalit and which immediately follow it shall have previously been set to exhibit danger.

Referring to the accompanying drawings, Figure 1 is a diagram illustrating the system broadly and showing the positions of the signaling devices when the trains are occupying the line. Fig. 2 is a front elevation of the Fig. 3 is a side elevation of the same, showing the locking. apparatus and commutator. Fig. 4 is an electrical diagram illustrating the interlocking of a signal-cross with the three signal crosses immediately in rear of it. Fig. 5 is also an electrical diagram showing the interlocking of each signal-cross represented with every other signal-cross in accordance with the connections shown in Fig. 4:. Fig.6 is an electrical diagram showing the interlocking of the four-armed crosses at the beginning of the line.

Similar letters and figures of reference inprovide a sprocket-wheel H on the shaft with a chain belt extending to a pulley H, rotated by a crank I at the lower part of the post, so that by turning said crank the signal-cross A B O D may be rotated. By means of a ratchet and pawl J, also on the shaft F, the said signal-cross is prevented from being rotated except in one direction. This being the disposition of affairs, it follows as a matter of course that after one arm, as C, Fig. 2, of the cross has been displayed in horizontal position all of the other arms 13 A D must be moved into similar position successively be fore the arm 0 can be displayed a second time. The arms A B D may be painted red to serve as danger-signals, and the arm 0 may be painted white to serve as a safety-signal. The post G is to be located in suitable proximity to the railway-line, so that the condition of the line ahead of the signal devices is indicated by whatever arm extends horizontally between the post and the track. I will defer explaining the interlocking mechanism for the present in order to first make clear the general arrangement of the system.

It is an obvious fact that the economical employment of any railway must depend upon the number of trains which simultaneously can be operated upon it with safety. It will also be apparent that as the speed of trains becomes increased the distance between them must be augmented and that therefore the on a perfectly-constructed electric railroad.

Diminished capacity of a line for trains, and hence reduction in its earning power, tends to reduce materially the advantage gained by the reduction in time due to the increased speed. My present invention is designed to reconcile these conflicting conditions, and it is organized in the following manner:

Having determined what shall be the maximum speed of the trains or vehicles which are to traverse the line and also having determined the space in which a given vehicle or train can be completely arrested by means of its brakes, I take that space or interval as the interval which is to separate the successive signaling devices,which, as Ihave stated, maybe crosses, as illustrated in Figs. 2 and 3. I further establish the fact that the normal condition of all the signaling devices before any train goes upon the line or while the line is unoccupied by trains shall be that each and every one of them shall exhibit a dangersignal. Reference to Fig. 2 will show that there are three positions of the cross in which it will show a danger-signalthat is to say, when it exhibits either arm A or B or D in the place of arm 0. Now I establish the further fact that the normal condition of each signal before any train goes upon the line or while the line is unoccupied is to be such that a single change, or, in other words, a quarterturn of the cross, will substitute the safetysignal for the danger-signal. Obviously, re-

fering once more to Fig. 2, this condition is realized (assuming the cross to rotate to the right of the drawings in the direction of the arrow) when the safety-signal arm 0 is in the position of the danger-signal arm 13. This condition is also represented diagrammatically by the four crosses g h M in Fig. 5, it being obvious that if any one of these crosses be rotated on its center to the right it will bring into horizontal position the white arm. I proceed now to the next proposition, which involves the consideration of a train or vehicle moving over the line and passing the signal-crosses successively. Now considering only one train, the following conditions supervene: As the train comes to the first signal-sta tion a safety-signal is shown, which it passes and reaches a second signal-station, where again a safety-signal is shown and passed, and so on. After the train passes a signal set at safety that signal is set at danger. Consequently as the train moves from one end of the line to the other it is constantly preceded, so to speak, by a safety-signal, while behind it danger-signals are shown. Now referring once more to Fig. 2, where the safetysignal 0 is shown displayed, it will be obvious that on the first quarter-turn to the right the arm B will have come into signaling position, and that on the succeeding quarter-turn the arm A will have come into signaling position, and on the next quarter-turn the arm D will have come into signaling position. Then and not until then will'the cross have reached its original normal position which it had before the safety-signal O was set, and which position is that which, as already stated, is represented in Fig. 5 at g h ii. In this way,

therefore, by simply rotating the three signals inrear of a train ahead one quarter-turn each all three of them can be kept at danger, and if these three signals are suitably interlocked with the signal which directly precedes the train .thenI may have not only a safety-signal constantly preceding the train as it passes over the line, but three signals following that train interlocked with that safety-signal in such a way as that that safetysignal cannot be put at safety unless these three following signals are at danger. Then I have still further this condition, that all other signals in rear of the train, except the three which guard it, are returned to their original danger position, so that the line is left ready to receive a second train, and in fact any number of trains which the line will accommodate.

To recapitulate, therefore, the signal-crosses are placed beside the railway-line succesively and separated by intervals, each equal to the space in which a train at maximum speed can be stopped by its brakes. These crosses are all set to show a danger-arm in the position represented at g h 2' j of Fig. 5, which isthe position in which a quarter-turn or one movement of rotation to the right will bring the safety-arm into exhibit position. These signal-crosses are so interlocked and operated.

that a train in traversing the line is always preceded by a safety-signal and followed by three danger-signals, which three danger-signals cannot be set to safety. Finally, in rear of these three signals which follow the train the signals are in their normal or original condition. This will be more clearly understood by reference to Fig. l of the drawings, which shows the line and the signals adjacent thereto in various successive positions. Beginning at the left, the railroad-line is represented in all cases by the line If, the signal: ing-crosses by the numbers 1 to 7. The train M already 011 the line is represented in successive positions at M M M M The following train is shown just coming on the line at N and in its successive positions at N N N N Still another train is shown coming on the line and following the train N at 0. Considering thetrain N, which first receives a safety-signal at 7, it passes to the position N. The safety-signal is shown at 6, and the danger-signal at 7. It passes to the position N Safety-signal is shown at 5, and danger-signals at 6 and 7. It passesto the position N and safety-signal is shown at 4 and dangersignals at 5, 6, and 7. We have now reached the condition when there is a safety-signal 4 in front of the train N and three danger-signals 5 6 7 in rear of it. It is obvious that the signal 7 in rear of the train N 3 has now been returned to its original positionna1nely,that shown at g h 2' j in Fig. 5-and if no more trains came on the line it would remain in that position indefinitely. Train N would go 011 to the position N preceded by the safety-signal 3 and followed by the dangersignals 4 5 6. But assume another train 0 follows. Then the signal 7 would be turned ahead a quarter of a revolution and the condition of aifairs would be precisely the same as appears in front of the train N. The relations of the signals between the succeeding trains are clearly shown in Fig. 1 and need no further explanation. Th us it will be noted that after the train M there are three danger-signals, then a safety-signal 4 in front of the train N and then again three dangersignals 5 6 7. Turning to the crosses shown in Fig. 5, there we have the condition of a single train on the line, with no following or preceding train. It will be seen that the signals a b c, as well as the signals g h z j, are all set in what I have hitherto termed the original and normal position and that the train represented at P and moving in the direction of the arrow has just passed the safety-signal d, which safety-signal is followed by three danger-signals e f g.

It will be observed that I have here provided for three danger-signals to follow the safetysignal, the object being not merely to give sufficient space for the following train to be stopped by its brakes in case it should run past a danger-signal, but a definite number of times that space, so as to adequately insure stoppage. For all practical purposes I think three times 'thespace will be sufficient, but I may decrease it to twice the space, or increase it to four or five times the space, making a corresponding modification in the number of signals displayed, or in the present specific contrivancein the number of signal-arms. Thus, to illustrate, and referring to Fig. 1, the train 0 may be stopped by its brakes in the space between the signals 6 and 7, also in the space between the signals 5 and 6, also in the space between the signals 4 and 5; but it has the entire space between signal 4 andsignal 7 in which to be stopped.

I come now to the interlocking mechanism, whereby it is made impossible to set the signal in front of the train to safety unless the three following signals are set at danger and also impossible to set any one of these three following signals at safety so long as a safety-signal precedes the-train guarded. The interlocking mechanism which I illus trate for this purpose is here electrical; but it may be-mechanical or constructed in any other Way so long as the results sought are represented by the lines klm with the signals 4 5' 6, while the signal 4: is connected by the interlocking mechanism represented by the lines at 0 19 with the signals 5 6 7, and so on.

Referring now to Figs. 3 and 4., on the shaft F of the signal-cross is a commutatorbarrel Q. .This may be of insulating material andprovided on its periphery With circuitclosing studs, one of which is shown at R. As each stud comes into suitable position it forces together contact-springs, and thus establishes circuit between these springs. springs are shown at Sin Fig. 3. Also on the shaft F is a locking-whee1 T, having four indentations. U is a pivoted dog adapted to engage with said locking-wheel. This dog is the armature of an electromagnet V. The mechanism described is inclosed in a suitable box WV and connected in circuit with feederlines X. The circuit arrangements will be best understood from Figs. 4 and 5. Here the commutator Q is shown developed as a series of successive circles, so as to exhibit the closing together of the'different pairs of springs by the projecting studs thereon.

It will of course be understood that all the developed circles in line transversely the page of the drawings with the. center of the signalcross 7' represent the positions of the circuitclosing pins or studs of the commutator be longing to that cross, and similarly all the circles in line with the signaling-cross 1' represent the positions of the studs of the commutator belonging to that cross, and so on, and the pins or studs of the commutator of each cross are arranged in a certain definite way with respect to the position of the arms The too

four signal-crosses, but the relation of the. circuit-closing studs of each commutator to the signal-cross to which it belongs. It is de- 1 sired to set the signal 0 a quarter-turn to the right, and hence to safety. This can be done because circuit is complete from the magnet 8, which controls the locking-dog 9 of the wheel 10 and is energized through the: This circuit is possible because the four commutators of the signals a d of each have a pin closing contact between the springs 12 13 14 15 and so circuit made by the wire 11.

making circuit between the positive and negative feeders Xthat is to say, the circuit from positive conductor X proceeds through the coil of magnet 8 and then through the closed-contact springs 12, 13, 14, and 15 to the negative conductor X. Now assume the signal-cross c to be turned a quarter of a turn to the right. The commutator of that cross will then also be rotated so as to close circuit at 40 and break it at 12. Then circuit will be made through the magnet 16 of the signalcross d. This circuit will proceed as follows:

from positive conductor X to magnet 16, to

closed contact springs 40, closed contact springs 19, to negative conductor X. Magnet 16 will then lift the locking-dog 17 out of the wheel 18, thus making it possible to set the signal cl a quarter of a turn ahead and so to danger. rotates its commutator, which breaks contact at 13 and 19 and establishes it at 20.

Circuit then proceeds from positive conductor X to magnet 21, to closed-contact springs 1 i turned its commutator then breaks circuit at 14 and 23 and closes circuit at 24. The circuit thus established proceeds from positive conductor X to magnet 25, to closed-contact springs 24, to closed-contact springs 24?, to negative conductor X. The magnet '25 thus energized raises the dog 26, so permitting the signal to be turned ahead one quarter-turn, which leaves that signal at danger and also in the position which I have defined as the normal position of all the signals on the line when no train is on it.

Turning now to Fig. 5, this shows not only the relation of simply four signals, as does Fig. 4, but also the relation of these four sig- The rotation of signal cl also nals to the other signals, and from this diagram the relation of any one of these signals to the interlocking mechanism may be readily traced. It will thus be clearly seen that the -interlocking mechanism here illustrated is fully competent to perform the object hitherto set out and to do so in a very simple and efficient manner.

I desire to call special attention to the fact that when the line is in its normal condition that is, unoccupied by trains-there is no expenditure of current, because all of the circuit-closing springs which establish circuit between the positive and negative feeders are open, and this state of afiairs prevails at every signal-station where the signal-cross is in the position of g h 'i j, or, as I have hitherto termed it, the normal position. It also follows that there is no expenditure of current except through the one signal immediately in advance of the train and the three signals immediately in rear of'it. Therefore the minimum amount of current is utilized to accomplish the desired result, or, to put it another way, every connection of the line is dead except those which are directly preceding the signal preceding the train and the three signals guarding its rear.

There is of course modification in the arrangementof the interlocking mechanism at the beginning of the line, and while such a modification would be obvious to the person skilled in the art I have illustrated it diagrammatically in Fig. 6. Here the signalcrosses gv h i j are all set in normal position. Assume a train to come in the direction of the arrow up to signal j. That signal can then be turned one quarter-turn to the right to exhibit the safety-arm, because circuit is made through its magnet 27 and the springs 28; but when signal j is turned one quarten turnahead its commutator breaks circuit at 28 and establishes it at 29. Therefore circuit is made through the magnet 30 of the signalcross 1 and that unlocks that signal-cross, so that it in turn can be set a quarter-turn ahead to give the oncoming train the safety-signal. The effect of that turn is to break circuit at 31 and establish it at 32, while also permitting the cross j to be turned forward another quarter-turn, thus closing circuit at 33. Circuit is then made through magnet 31 of signal It, so that that signal may be set ahead a quarter-turn. The result is to break circuit at 33 and close circuit at 34, while signals 1. j may each now again be set forward a quarterturn, closing circuit at 35 and 36, thus energizing magnet 37 to release its lock and so allow signal g to be turned ahead a quarter turn. The net result is that before the second signal-namely,- signal z'can be put to safety signal j must be put to danger, before the third signal 71. can be put to safety both signals 2' j must be at danger, and before the fourth signal g can be set to safety all three preceding signals h t' j must be set at danger. This is the condition which, as already explained, prevails so long as the train is on the line.

I claim- 1. In a railroad signal system, a railwayline, a single series of signaling devices in proximity thereto, each device being constructed to exhibit a dangersignal and a safety-signal, and interlocking mechanism connecting each device with two or more immediately-succeeding signaling devices; the said devices being constructed and arranged so that a given device cannot be set to exhibit a safety-signal ahead of a train until it shall have exhibited a danger-signal as many times as there are succeeding devices interlocked with it in rear of said train, and unless said succeeding devices sh all previously have been set to exhibit danger, substantially as described.

2. In a railroad signal system, a railwayline, a single series of signaling devices in proximity thereto, each device being constructed to exhibit a danger -signal and a safetysignal and interlocking mechanism connecting said devices; the-said devices and interlocking mechanism being constructed and arranged so that each device successively from one end of the line to the other may be set to exhibit a safety signal ahead of a train provided the two or more immediately-succeeding devices in rear of said train are previously set to exhibit danger, substantially as described.

3. In a railroad signal system, a railwayline, a' single series of signaling devices in proximity thereto, each device being constructed to exhibit a danger-signal and a safetysignal and interlocking mechanism connecting said devices; the said devices and interlocking mechanism being'constructed and arranged to exhibit a danger-signal everywhere when the line is unoccupied, and so that each device having once been set to safety cannot again be so set until it shall have exhibited a danger-signal as many times as there are succeeding devices interlocked with it, substantially as described.

4. In a railroad signal system, a single series of signal devices each having a safetysignal and a danger-signal, means for actuating said signals to' cause them to be displayed, a locking device engaging with said means, circuit-closing devices controlled by said means, an electromagnet controlling said locking device and circuit connections substantially as set forth; whereby the said signaling devices are interlocked so that the safety-signal of one device cannot be exhibited ahead of a train unless the danger-signals of two or more succeeding signaling devices in rear'of said train are also exhibited, substantially as described.

5. Ina railroad signal system, a single se-' ries of signal devices each having a signalarm indicating safety and a signal-arm indicating danger, a rotary shaft actuated coincidently with said arms, a locking device engaging with said shaft, an electrolnagnet controlling said locking device, circuit-closing devices controlled by said shaft and circuit connections substantially as set forth; whereby the said signaling devices are interlocked so that the safety-signal of one device cannot be exhibited ahead of a train unless the danger-signals of two or more succeeding signaling devices are also exhibited in rear of said train, substantially as described.

' CHARLES H. DAVIS.

Witnesses:

F. O. BARTLETT, H. R. MOLLER. 

